1. Field of the Invention
The present invention relates to a wireless selective call receiver in which a power supply is turned off at the time of abnormal reception so that battery power consumption can be reduced.
2. Description of the Related Art
In a conventional wireless selective call receiver, when the data which is not interleaved is received and two continuing words of the data have BCH (binary decimal) code errors, the reception is determined to be abnormal so that a power supply of the receiving section is turned off.
Also, an interleaved data is recently transmitted so as to increase the access speed to a memory. In this case, the determination of the abnormal reception mentioned above based on the BCH error can not be performed because the data is deinterleaved into a plurality of words in the form of the BCH code at the reception side.
FIGS. 1A to FIG. 3 are the diagrams which show examples of the above-mentioned interleaving and deinterleaving operations.
First, one word is composed of x bits as shown in FIG. 1B, and one block is composed of y words as shown in FIG. 1A. In this case, the data is transmitted in the order from the first bit of the word 0, to the first bit of the word y, and subsequently from the second bit of the word 0 to the second bit of the word y, and then from the x-th bit of the word 0 to the x-th bit of the word 0 in the interleaving operating, as shown in FIG. 2. Thus, as shown in FIG. 3, even if the data containing errors is continuously received, error bits are distributed in each of words, when the interleaving state is eliminated, that is, the deinterleaving operation is performed. Here, error words or error bits are enclosed by square frames in FIGS. 2 and 3.
Therefore, the number of error bits within each word becomes small. That is, with the interleaved data, even if it supposes that any error is present over continuing words, the error data bits have been equally distributed into the respective word after the deinterleaving operation. Accordingly, the number of error bits becomes small in each word and each word is determined to be normal for the BCH code. Also, in the deinterleaved data, there is less case that the BCH errors continue because the error data bits are distributed in respective words in the deinterleaving operation.
In the reception of the data which is not interleaved, in the conventional wireless selective call receiver, the power supply of the receiving section is turned off, when two continuing words have BCH errors together. Therefore, there is a problem in that the power supply to the receiving section continue to be in the on state for a long time even if the data contains any BCH errors so that the battery lifetime becomes short.
Also, in the wireless selective call receiver in which interleaved reception data is deinterleaved, the number of error bits for every word becomes small. Accordingly, there is another problem in that the determination of reception data to be normal or abnormal can not be correctly implemented.
In addition, in Japanese Laid Open Patent Disclosure (JP-A-Heisei 7-115674), a wireless selective call receiver is described. In this reference, a receiving circuit is turned on only for frames corresponding to the receiver and when the same ID as that of the receiver is not found in the second word, the power supply to the receiving section is stopped.
The present invention is accomplished to solve the problems described above. An object of the present invention is to provide a wireless selective call receiver in which the determination of abnormal reception is performed when the number of words having error bits exceeds a predetermined value such that the abnormal reception is stopped.
Another object of the present invention is to provide a wireless selective call receiver in which the power supply to a receiving section is turned off to shorten the power supply on time in the abnormal reception, resulting in prolongation of battery life.
In order to achieve an aspect of the present invention, a wireless selective call receiver includes a receiving section for receiving an interleaved data signal sequentially in units of bits, the interleaved data signal being generated by interleaving a data composed of a plurality of words, for deinterleaving the received data signal to produced a deinterleaved data signal corresponding to the plurality of words, and for detecting a message from the deinterleaved data signal, and a control unit for stopping an operation of the receiving section not to perform when a number of words containing BCH error bits equal to or more than a first predetermined number exceeds a second predetermined number.
The wireless selective call receiver may further include a power source, and the control unit stops supply of power from the power source to the receiving section when the number of words containing error bits equal to or more than the first predetermined number exceeds the second predetermined number. The data includes a plurality of blocks, and the receiving operation by the receiving section is controlled to be performed or not to be performed in units of blocks.
Also, the control unit may include a BCH error detecting circuit for detecting the BCH error bits of each of the plurality of words corresponding to the deinterleaved data signal, an error word counter for counting the words as error words having the BCH error bits equal to or more than the first predetermined value, a comparing section for comparing the second predetermined value and the count value of the error words, and an operation control circuit for stopping the operation of the receiving section when it is determined that the count value of the error words exceeds the second predetermined value. The wireless selective call receiver may further include a power source. In this case, the operation control circuit stops supply of power from the power source to the receiving section when it is determined that the count value of the error words exceeds the second predetermined value. Also, the data includes a plurality of blocks, and the receiving operation by the receiving section is controlled to be performed or not to be performed in units of blocks.
In order to achieve another aspect of the present invention, a method of controlling a receiving operation in a wireless selective call receiver, includes the steps of:
receiving an interleaved data signal sequentially in units of bits, the interleaved data signal being generated by interleaving a data composed of a plurality of words;
deinterleaving the received data signal to produced a deinterleaved data signal corresponding to the plurality of words;
detecting a message from the deinterleaved data signal;
stopping an operation of the receiving section not to perform when a number of words containing BCH error bits equal to or more than a first predetermined number exceeds a second predetermined number.